Conversion convergent nozzle assembly

ABSTRACT

A convergent nozzle assembly (10) includes a generally cylindrically-shaped nozzle (52) engaged over a diffuser (40) extending forwardly from the gooseneck (26) of a hand piece (22) of a continuous wire electrode (14), inert gas shielded arc welding unit (12). The nozzle (52) also extends over an electrically conductive tip (35) extending forwardly from the diffuser (40). The interior of the nozzle (52), being of a larger diameter than the exterior of the diffuser (40), defines an air or gas collection cavity (51) therebetween to receive pressurized air or gases through cross holes (50) to intersect the central bore (48) of the diffuser (40) with the collection cavity (51). A plurality of passageways (64) direct the pressurized air or gas from the collection cavity (51) forwardly to discharge such air or gas forwardly from the nozzle assembly (10) to converge with each other at approximately the location at which the endless wire electrode (14) intersects the workpiece being cut or gouged.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 329,793,filed Mar. 28, 1989, now U.S. Pat. No. 5,041,710, which is acontinuation-in-part of U.S. patent application Ser. No. 142,074, filedJan. 11, 1988, now abandoned.

TECHNICAL FIELD

The present invention concerns a nozzle assembly for use in metalcutting and gouging, and more particularly, a nozzle assembly to convertan inert gas shielded welding unit into an efficient arc cutting and arcgouging torch.

BACKGROUND OF THE INVENTION

One of the most common general purpose type of welding system utilizes acontinuous wire electrode that is fed from a coil through a wire drivemechanism to push the wire electrode through the interior of a flexiblecable, through a hand piece at the end of the cable and finally throughan electrically conductive tip extending forwardly of the hand piece.The tip receives high amperage current from a power supply typicallymounted on a cart, together with the wire drive mechanism and a reel ofthe consumable wire electrode. To shield the area being welded fromatmospheric oxygen, an inert gas is also supplied through the cableassembly, the hand piece and discharged through a nozzle at the forwardend of the hand piece as an annular skirt or cloud about the electrodetip. Commonly used inert gases include argon, helium and carbon dioxide.The annular stream of inert gas is supplied at a relatively lowpressure, for instance at about 30 pounds per square inch and about 30cubic feet per hour, which is sufficient to prevent the extraction fromthe ambient air of contaminants such as oxygen or nitrogen that can havea deleterious effect on the metal being welded. Examples of this type ofwelding system are disclosed by U.S. Pat. Nos. 2,761,049, 2,833,913, and3,265,856.

When desiring to cut or gouge metal rather than weld metal, a differenttype of electric arc apparatus is employed. One common type of apparatusfor this purpose is known as the arc-air torch. The arc-air torchutilizes an electrically charged electrode which may be in the form of asolid, stiff carbon electrode rod initially approximately one to twofeet long and consumed during the cutting or gouging process. The rod isheld within the jaws of a hand-held clamp to enable the welder to movethe tip of the electrode along the cutting path. Compressed air,typically at about 60 to 100 pounds per square inch, is directed at thetip of the electrode to continually blow away the molten metal.

To both weld and cut metallic materials efficiently two different typesof apparatus have been required, i.e., a gas shielded arc welder and anarc-air cutting torch. Heretofore, this has required an investment thatoften has been too large for small shops, farms and ranches, especiallysince these tools may not be used on a daily basis.

SUMMARY OF THE INVENTION

The present invention provides a novel nozzle assembly to efficientlyand economically convert a continuous electrode wire, inert gas shieldedarc welding unit into an arc cutting and gouging apparatus. Theconversion nozzle assembly is composed of a longitudinal nozzleextending over a diffuser attached to the forward end of the gooseneckof the hand piece of the welding unit and also over an electricallyconductive tip extending forwardly from the diffuser. The nozzle isthreadably or otherwise securely connected to the rear portion of thediffuser. A collection cavity is either formed entirely by the diffuseror by exterior portions of the diffuser and interior portions of thenozzle for receiving pressurized air or gas which is supplied to thecentral bore of the diffuser, through which bore the electrode wire alsopasses. In the situation in which the collection cavity is cooperativelyformed by the diffuser and nozzle, cross holes extend radially outwardlythrough the diffuser to direct the pressurized air or gas from thediffuser central bore to the collection cavity. A plurality ofpassageways extend longitudinally forwardly from the collection cavitythrough either the diffuser or nozzle, to terminate at outlet openingsoriented to direct the jets of compressed air or gas flowingtherethrough to converge at the electrode wire at a location in front ofthe nozzle assembly and blow away the molten metal.

In accordance with a further aspect of the present invention, at leastportions of the nozzle assembly are composed of electrically insulatingmaterials to insulate the exterior of the nozzle from the electricallyconducting diffuser and contact tip. This is desirable not only for thesafety of the operator, but also to avoid the creation of a closedelectrical circuit when the exterior of the nozzle assembly touchesagainst a workpiece.

In accordance with another aspect of the present invention, the nozzleis essentially in the form of an elongate cylindrical member having aseparate rearward collar member disposed between the interior diameterof the cylindrical member and the exterior diameter of the diffuserthereby to secure the nozzle assembly to the diffuser. A relativelylarge counterbore is formed in the rearward portion cylinder to receivethe collar and to define the collection cavity between the insidediameter of the nozzle and the outside diameter of the diffuser at alocation forwardly of the collar. A smaller diameter bore extendslongitudinally through the forward portion of the cylindrical member tosnugly engage over the forward portion of the diffuser and theelectrically conductive tip.

In accordance with yet another aspect of the present invention, thenozzle assembly includes a rearward cylinder having an inside diameterlarger than the width or exterior diameter of the diffuser thereby todefine a collection cavity between the exterior of the diffuser and theinside diameter of the cylinder. The cylinder is secured to the diffuserby a collar positioned rearwardly of the cross holes formed in thediffuser through which compressed air or gas is transmitted to thecollection cavity from the hollow interior of the diffuser. The collarsnugly engages over the rear exterior portion of the diffuser and snuglyengages within the rear interior portion of the cylinder. The nozzleassembly also includes a forward, generally frustoconically-shaped nosedetachably connected to the forward end of the rearward cylinder. Theinterior of the rearward portion of the nose is also hollow inconstruction to form a continuation of the collection cavity defined bythe interior of the cylinder. A plurality of relatively smallpassageways extend forwardly from the hollow rear portion of the nose todischarge the compressed air or gas in forwardly directed jet streams.Preferably, the passageways are oriented to converge the air jet streamsinwardly in the forward direction to cause them to intersect at a pointsomewhat forwardly of the nozzle assembly thereby to concentrate the jetstreams at approximately the forward tip of the wire electrode in themolten metal puddle.

BRIEF DESCRIPTION OF THE DRAWINGS

The details of typical embodiments of the present invention will bedescribed in connection with the accompanying drawings, in which:

FIG. 1 is a pictorial view of a typical continuous wire electrode, inertgas shielded welding unit which is converted into an arc cutting andgouging torch through the use of the present invention;

FIG. 2 is a pictorial view of a conversion nozzle assembly constructedaccording to the present invention;

FIG. 3 is a pictorial view of a second preferred embodiment of aconversion nozzle assembly constructed according to the presentinvention;

FIG. 4 is a cross-sectional view of the conversion nozzle assemblyIllustrated in FIG. 2;

FIG. 5 is a front view of the conversion nozzle assembly illustrated inFIGS. 2 and 4;

FIG. 6 is a cross-sectional view of the conversion nozzle assemblyIllustrated in FIG. 3;

FIG. 7 is a front view of the conversion nozzle assembly shown in FIGS.3 and 6;

FIG. 8 is a pictorial view of another preferred embodiment of theconversion nozzle assembly constructed according to the presentinvention;

FIG. 9 is a cross-sectional view of the conversion nozzle assemblyillustrated in FIG. 8;

FIG. 10 is a front view of the conversion nozzle assembly shown in FIGS.8 and 9; and,

FIG. 11 is a cross-sectional view of a further preferred embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE INVENTION

Referring initially to FIG. 1, a nozzle assembly 10 constructedaccording to the present invention is utilized to convert typicalcontinuous wire electrode inert gas shielded welding units, such as awelding unit 12, into an arc cutting or gouging torch. The typical inertgas shielded welding unit 12 includes a thin, continuous wire electrode14 wound on a spool 16. The wire electrode 14 is fed from the spool 16through a wire drive mechanism 18 to push the wire through the center ofa flexible cable 20 that terminates at a manually graspable hand piece22. The hand piece 22 includes a trigger 24 for feeding the wireelectrode 14 through the cable 20 when desired. A curved gooseneck 26 isattached to the forward end of the hand piece 22 to direct the wireelectrode 14 from the hand piece and into the nozzle assembly 10 of thepresent invention. The cable 20, hand piece 22 and gooseneck 26 all havea hollow central interior or bore 30 through which the wire electrode 14is fed, and which interior is large enough to also route therethrough aninert shielding gas, such as argon, helium or carbon dioxide. Inaddition, the cable 20, hand piece 22 and gooseneck 26 include internalelectrically conductive members 32 to route high amperage current from apower supply 34 to an electrically conductive tip 36 disposed within theforward end of the nozzle assembly 10. The flow of the shielding gas andthe supply of the high amperage current to the electrically conductedcontact tip 36 are also controlled by the trigger 24. As illustrated inFIG. 1, the power supply 34, the wire feed mechanism 18 and the wirespool 16 may all be mounted on a wheeled cart 38 for ease of movementfrom location to location.

The foregoing description of a typical continuous wire electrode inertgas shielded welding unit is merely illustrative of such units and isnot inclusive of the types of such welding units with respect to whichthe present invention may be utilized. Such welding units are known inthe art and do not per se constitute the present invention.

Next referring specifically to FIGS. 2, 4 and 5, the conversion assembly10 is constructed with an elongated, electrically conductive diffusermember 40 having a threaded connection section 42 extending rearwardlyfrom a flange 44 to threadably engage within the correspondinglythreaded interior of the forward end portion of the gooseneck 26. Thediffuser 40 includes a major shank section 46 extending forwardly fromthe flange 44 to threadably engage with the rearward end portion of theelectrically conductive tip 36. As illustrated in FIG. 4, the centralinterior 48 of the diffuser 40 is hollow or in the form of a centralbore to receive both the wire electrode 14 and the inert shielding gasflowing through the central interior of the gooseneck. As such, thediffuser interior 48 is of a diameter somewhat larger than the outerdiameter of the wire electrode 14. The conductive tip 36 also includes acentral bore 49 extending therethrough, however, of a size smaller thanthe bore 48 formed in the diffuser member 40 so as to closely andslidably receive the wire electrode 14, but to prevent leakage of anyappreciable volume of the gas or air.

A plurality of cross holes 50 are formed in the shank section 46 of thediffuser 40 to direct the shielding gas from the central bore 48 of thediffuser and into a collection cavity 51 defined by the exterior of thediffuser and the interior portions of a generally cylindrically-shapednozzle 52 which extends forwardly from the gooseneck 26 to approximatelythe forward end of the contact tip 36. The nozzle 52 is attached to thediffuser 40 by a collar 54 that is snugly and threadably engaged withthe portion of the shank section 46 extending rearwardly from thecollection cavity 51 to the diffuser flange 44. The collar 54 includes arear flange 56 which abuts against the rear end of the nozzle 52 andagainst the adjacent forward surface of the diffuser flange 44. Theouter diameter of the collar 54 snugly engages within a counterbore 58formed in the rearward portion of the nozzle 52, which counterbore alsodefines the collection cavity 51. The nozzle 52 includes a secondsmaller diameter counterbore 60 which snugly receives the shank section46 of the diffuser 42 located forwardly of the cross holes 50 and thecollection cavity 51. The nozzle 52 is formed with a third, central boresection 62 which snugly receives the electrically conductive tip 36therein.

A plurality of air or gas passageways 64 extend through the nozzle 52forwardly from the collection cavity 51 and then angle inwardly atforward portions 66 thereby to discharge gaseous jets in streams thatconverge toward the wire electrode 14 at a location forwardly of thenozzle assembly 10. Ideally this convergence location corresponds to thelocation at which the metal being cut or gouged is in a molten state,i.e., the location of the arc existing between the wire electrode 14 andthe workpiece. Although three passageways 64 are illustrated in FIGS. 4and 5, it is to be understood that the number of passageways may beincreased or decreased to accommodate various factors, such as the typeand size of the electrode wire 14 being utilized, the thickness andcomposition of the workpiece being cut or gouged, the amperage of thecurrent supplied to the electrode, etc.

Ideally nozzle 52 and collar 54 are at least in part constructed fromelectrically nonconductive, heat resistant material thereby to insulatethe electrically conducting diffuser 46 and tip 36 from the exterior ofthe nozzle assembly 10. Examples of such nonconductive, heat resistantmaterials may include, for instance, plastics such as nylon, ornonconductive ceramics.

In operation, the inert gas shielding nozzle (not shown) which isemployed when the unit 12 is used for welding, is detached from thegooseneck 26 and replaced with the conversion convergent nozzle assembly10 of the present invention to provide a convergent gas or air streamthat removes molten metal from the arc puddle. If the welding nozzleutilizes a diffuser and conductive tip similar to the diffuser 46 andconductive tip 36 shown in FIG. 4, then these components of the weldingnozzle may also be employed as part of the conversion convergent nozzleassembly 10 of the present invention. This reduces the number of newcomponents required to construct the conversion convergent nozzleassembly 10.

To employ the unit 12 as a cutting or gouging tool, the same wireelectrode used during welding may be used during the arc cutting orgouging process. As an example, tubular wire electrodes are commonlyemployed for welding. Such electrodes have a center core composed of thesame base material from which the components being welded are composed.During the arc cutting or gouging process, use of such tubular wireelectrodes provides increased metal removal by producing a larger, morefluid molten puddle. As an alternative, a continuous solid wire, tubulargas-producing filler or carbon-filled wire electrode may be used for thearc cutting or gouging process.

Also, in the present invention, either welding polarity, REP (reversepolarity-electrode positive) or SEN (straight polarity-electrodenegative) may be used. SEN will, however, provide a larger weldingpuddle for metal gouging or cutting than provided by REP. The metalremoval rate may be maximized by increasing the operating voltage to themaximum level available from the welding power supply 34.

To provide the converging jet stream for blowing molten metal away fromthe tip of the electrode, the same inert gas used during the weldingprocess may be employed or the inert gas supply may be disconnected fromthe unit 12 and replaced with compressed air, for instance, from astandard air compressor. If the inert welding gas is used, the supplypressure of the gas may have to be increased somewhat to generate astream of gas of sufficient velocity to remove the molten metal. Thisgenerally is not a problem if compressed air is used, for instance, fromthe shop supply air, in that such air is typically in the range of from80 to 100 pounds per square inch. It will be appreciated that mostlikely the use of compressed air will be less expensive than if theinert shielding gas is used. However, if the amount of metal to be cutor removed is quite small, this cost differential may not besignificant. Further, in conjunction with the present invention, the useof reactive gases, such as oxygen, nitrous oxide or flammable fuels,should be avoided to prevent uncontrolled reactions during the cuttingor gouging process.

With the foregoing minimal changes, the unit 12 is ready to be used as acutting and gouging tool with the compressed air or inert gas flowingthrough the center of the cable 20, hand piece 22, gooseneck 26 and intothe central bore 48 of the diffuser 40. From the central bore 48, thecompressed air or inert gas is transmitted to the collection cavity 51through the radial cross holes 50 extending through the shank section 46of the diffuser 40. From the collection cavity 51, the compressed air orinert gas flows forwardly through the passageways 64 and then outthrough the forward portions 66 of the passageways to converge into asingle stream at the location of the molten metal thereby to blow themolten metal away from the tip of the electrode wire 14.

It will be appreciated that by virtue of the present invention, atypical inert gas shielded welding unit utilizing an endless wireelectrode may be conveniently and very economically converted into anefficient arc cutting or gouging tool. As such, it is not necessary forsmall shops, farms, ranches, etc. to invest in both a gas shieldedwelding unit and a separate arc or other metal removal torch ormechanism.

A further embodiment of the present invention is illustrated in FIGS. 3,and 7 wherein the components comparable to those shown in FIGS. 2, 4,and 5 are indicated with the same part numbers but with the addition ofa "prime" designation. To avoid repetition, the construction of theseparticular components will not be repeated.

FIGS. 3, 6 and 7 illustrate a nozzle assembly 70 having a rearwardcylindrical portion 72 extending forwardly from the gooseneck 26' tothreadably engage with a forward nose assembly 74 which extends slightlyforwardly of the forward end of the contact tip 36'. As shown in FIG. 6,the cylindrical portion 72 extends along the nozzle assembly 70forwardly from the gooseneck 26' approximately to the location at whichthe diffuser shank 46' intersects the contact tip 36'. Further, theinside diameter of the cylindrical portion 72 is larger than theexterior diameter or width of the diffuser shank section 46' thereby todefine a collection cavity 76 adjacent cross holes 50'. The cylindricalportion 72 is secured to the rear connector portion 42' of the diffuser40' by a collar 78 which snugly and threadably engages with both thethreaded and unthreaded sections of the rear connector portion 42'. Anelectrically insulating sleeve 80 is disposed between the outsidediameter of collar 78 and an inside diameter of cylinder portion 72thereby to electrically insulate the cylinder portion from the gooseneckend 26' and diffuser shank 46'.

The nose assembly 74 includes an exterior, generallyfrustoconically-shaped nose 82 having a hollow, rearwardly extendingpilot hub 84 formed with external threads to engage with the internalthreads formed in the forward end portion of the cylinder 72. Theinterior portion of the pilot hub 84 forms an extension of thecollection cavity 76 and intersects with a cavity section 86 formed inthe rearward or base portion of nose 82. A plurality of air or gaspassageways 88 extend forwardly from the cavity section 86 to breakthrough the forward end of the nose 82 so that the pressurized air orgas disposed within the collection cavity 76 and the cavity section 86is discharged from the passageways in discrete jets that converge towardthe wire electrode 14' at a location somewhat in front of the forwardend of the nose assembly 70. Although four passageways 88 areillustrated in FIGS. 6 and 7, it is to be understood that their numbermay be 5 increased or decreased depending upon various factors, such asthe diameter of the passageways, the size of the wire electrode 14'being utilized, the type of metal being cut or gouged, the amperage ofthe electrical current being applied to the electrode, the arc voltage,etc.

The nose assembly 74 also includes a spacer in the form of anair-sealing insulator 90 having a generally circularly-shaped rearwardsection abutting against the forward end of the diffuser shank 46' and afrustoconically-shaped forward section bearing against acorrespondingly-shaped seat 92 formed within the interior of the nose 82to form an airtight seal. At its forward end, the seat 92 intersectswith a longitudinal bore 94 formed in the forward interior portion ofthe nose 82 to provide clearance for the contact tip 36'. Ideally, thespacer/airsealing insulator 90 is composed at least in part ofelectrically insulating material to insulate the nose 82 from thecontact tip 36'. The spacer also serves to prevent air or gas in cavity86 from leaking into bore 94.

As discussed above with respect to nozzle assembly 10, if the weldingunit 12 includes a diffuser and contact tip similar to the diffuser 40'and tip 36' shown in FIG. 6, then the nozzle assembly 70 of the presentinvention may utilize these components. The same is true if the weldingunit includes a cylindrical portion and an attachment collar similar tothe cylindrical portion 72 and the collar 78 shown in FIG. 6. Moreover,the nozzle assembly 70 functions in essentially the same manner as thenozzle assembly 10 discussed above, and as such, provides the sameefficiencies and other advantages provided by the nozzle assembly 10.

Another preferred embodiment of the present invention is illustrated inFIGS. 8, 9 and 10, wherein components comparable to those in FIGS. 1-7are indicated with the same number but with the addition of a "doubleprime" (") designation. To avoid repetition, the construction of theseparticular components will not be repeated. FIGS. 8, 9 and 10 illustratea conversion convergent nozzle assembly 100 constructed with anelongated, electrically conductive diffuser 102 having a rearward,reduced diameter connection section 104 to threadably engage within thecorrespondingly threaded interior of the forward end portion of thegooseneck 26". The diffuser extends forwardly from the gooseneck 26"within the interior of a surrounding nozzle assembly 106. The diffuser102 is formed with a forward counterbore 108 for closely receiving anelectrically conductive tip 36" that extends slightly forwardly of theforward end of the diffuser. The tip is constructed with a reduceddiameter rearward threaded portion 110 to engage a correspondinglythreaded portion of the central interior of the diffuser. A smalldiameter bore 49" extends longitudinally through the center of theconductive tip 36" for closely and slidably receiving the electrode wire14".

As illustrated in FIG. 11, the diffuser and electrically conductive tipmay be constructed as one integral unit 128 of electrically conductivematerial. Other than this difference, the convergent conversion nozzleassembly 130 shown in FIG. 11 is the same as that shown in FIGS. 8-10,and thus, like parts are given the same part number but with a "tripleprime" ('") designation. One advantage of constructing diffuser 102 andtip 36" as separate components is that commercially available tipscorresponding to tip 36" may be utilized in conjunction with the presentinvention.

The diffuser 102 is formed with a rear counterbore 112 in the region ofthe connection section 104. The counterbore 112 is of a diameter largerthan the central bore 30" of the gooseneck 26" thereby to serve as acollection cavity for the air or gas flowing through the center of thegooseneck and also to permit passage of the wire electrode 14" whichthen extends through a smaller diameter bore section 48" of the diffuserof a size somewhat larger than the outer diameter of the wire electrode14". The wire electrode 14" next enters the central bore 49" extendingthrough the conductive tip 36", which bore size preferably is smallerthan the bore 48" formed in a diffuser so as to closely and slidablyreceive the wire electrode 14", but to prevent leakage of anyappreciable volume of the gas or air received from the gooseneck 26".

A plurality of relatively small diameter air/gas passageways 114 extendforwardly from the diffuser collection cavity 112 to discharge from thediffuser gas/air jets in streams that converge toward the wire electrode14" at a location forwardly of the nozzle assembly 100. Ideally thisconvergence location corresponds to the location in which the metalbeing cut or gouged is in a molten state thereby to efficiently andeffectively blow the molten metal away from the workpiece. In therearward portion of the diffuser, the passageways 114 initially areangled outwardly away from the longitudinal center of the diffuser andthen in the forward portion of the diffuser, the passageways are angledinwardly toward the longitudinal center of the diffuser thereby todirect the air/gas streams in the desired converging pattern. Althoughfour passageways 114 are illustrated in FIGS. 9 and 10, it is to beunderstood that the number of passageways may be increased or decreasedto accommodate various factors, such as the type and size of theelectrode wire 14" being utilized, the thickness and composition of thework piece being cut or gouged, and amperage of the current supply tothe electrode, etc.

The nozzle assembly 106 includes a rearward cylindrical section 116which is snugly engaged over the rear portion of the diffuser 102 andthe forward portion of the gooseneck 26" through the intermediacy of aninsulating sleeve 118 composed of electrically nonconductive material ina manner similar to collar 54 and sleeve 80 thereby to electricallyinsulate the nozzle assembly 106 from the diffuser. The nozzle assemblyalso includes a forward section 120 engagable with the leading end ofthe nozzle rear section 116. Ideally the front of the forward section120 corresponds with the front of the diffuser 102, as shown in FIGS. 8and 9.

The nozzle assembly 100 shown in FIG. 10 though different inconstruction from those shown in FIGS. 1-7, provides the sameefficiencies and numerous other advantages provided by the nozzleassemblies 10 and 70.

As will be apparent to those skilled in the art to which the inventionis addressed, the present invention may be embodied in forms other thanthose specifically disclosed above without departing from the spirit orscope of the present invention. The particular embodiments of the nozzleassemblies 10, 70, 100 and 130 set forth above are therefore to beconsidered in all respects as illustrative and not restrictive. Thescope of the present invention is as set forth in the appended claimsrather than being limited to the examples of the nozzle assemblies 10,70, 100 and 130 described in the foregoing description.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A convergent nozzleassembly to convert an inert gas shielded welding unit into an arccutting and gouging torch, the conversion convergent nozzle assemblycomprising:(a) a cylindrical diffuser having a central bore sized topermit passage of a continuous wire electrode and a stream of gas from aremote source sufficient to blow molten metal away from the location ofcutting or gouging with the torch; (b) an electrically conductivecontact tip extending forwardly from the diffuser, the contact tiphaving a central bore sized to slidably and closely receive the wireelectrode; (c) a longitudinal nozzle extending over the diffuser and thecontact tip; (d) a connection cavity formed at least partially by thediffuser for receiving the gas stream from the remote source; and (e) aplurality of gas passageways extending longitudinally forwardly from thecollection cavity, the gas passageways each including a forward section,each forward section terminating in an outlet opening and being orientedto direct the individual gas streams flowing through the gas passagewaystoward a convergence point located forwardly of the nozzle assembly. 2.The conversion convergent nozzle assembly according to claim 1, whereinthe gas passageways further include rear sections in gas receivingcommunication with the collection cavity and extending through thenozzles to the forward sections.
 3. The conversion convergent nozzleassembly according to claim 2, wherein the gas collection cavity isdefined by the exterior of the diffuser and the interior of the nozzle.4. The conversion convergent nozzle assembly according to claim 3,wherein the diffuser includes holes extending outwardly from the centralbore of the diffuser to the gas collection cavity.
 5. The conversionconvergent nozzle assembly according to claim 1, further comprisingmeans for attaching the nozzle to the diffuser at a location spaced fromthe collection cavity.
 6. The conversion convergent nozzle assemblyaccording to claim 5, wherein the attaching means are composed at leastin part of electrically insulated material to electrically insulate theexterior of the nozzle from the diffuser.
 7. The conversion convergentnozzle assembly according to claim 5, wherein the attaching means form agas tight seal between the nozzle and the diffuser at a location spacedrearwardly from the collection cavity in the direction opposite to thetip.
 8. A conversion convergent nozzle assembly to convert an inert gasshielded welding unit into an arc cutting and gouging torchcomprising:(a) an elongate diffuser having a longitudinal, central boresized to permit passage of a continuous wire electrode and a stream ofgas contiguous with the wire electrode, from a remote source and in asufficient volume and flow rate to blow molten metal away from thelocation of the cutting or gouging of a work piece with the torch; (b)an electrically conductive contact tip having a central bore incommunication with the central bore of the diffuser and sized toslidably and closely receive the wire electrode; (c) a longitudinalnozzle extending over the diffuser; (d) a collection cavity formedwithin the diffuser for receiving the gas stream from the remote source;and (e) a plurality of gas passageways extending longitudinallyforwardly from the collection cavity and through the diffuser, thepassageways each including a forward section, each forward sectionterminating in an outlet opening and being oriented to direct theindividual gas streams flowing through the diffuser toward a convergencepoint located forwardly of the nozzle assembly to blow molten metal awayfrom the location of the cutting or gouging of the work piece with thetorch.
 9. The conversion convergent nozzle assembly according to claim8, further comprising means for electrically insulating the nozzle fromthe electrically conductive contact tip.
 10. The conversion convergentnozzle assembly according to claim 8, wherein the nozzle includes atleast an electrically nonconductive portion to prevent electricalconduction between the tip and the nozzle.
 11. A convergent nozzleassembly to convert an inert gas shielded welding unit into an arccutting and gouging torch, the conversion convergent nozzle assemblycomprising:(a) a cylindrical diffuser having a central bore sized topermit passage of a continuous wire electrode and a stream of gas from aremote source sufficient to blow molten metal away from the location ofthe cutting or gouging with the torch; (b) an electrically conductivecontact tip extending forwardly from the diffuser, the contact tiphaving a central bore sized to slidably and closely receive the wireelectrode; (c) a longitudinal nozzle extending over the diffuser and thecontact tip and including at least an electrically nonconductive portionto prevent electrical conduction between the tip and nozzle; (d) acollection cavity formed at least partially by the diffuser forreceiving the gas stream from the remote source; (e) a plurality of gaspassageways extending longitudinally forwardly from the collectioncavity, the passageways having outlet openings oriented to direct theindividual gas streams flowing through the gas passageways toward aconvergence point located forwardly of the nozzle assembly; and (f) ameans for preventing electrical conduction between the tip and thenozzle.
 12. A convergent nozzle assembly to convert an inert gasshielded welding unit into an arc cutting and gouging torch, theconversion convergent nozzle assembly comprising:(a) a cylindricaldiffuser having a central bore sized to permit passage of a continuouswire electrode and a stream of gas from a remote source sufficient toblow molten metal away from the location of cutting or gouging with thetorch; (b) an electrically conductive contact tip extending forwardlyfrom the diffuser, the contact tip having a central bore sized toslidably and closely receive the wire electrode; (c) a longitudinalnozzle extending over the diffuser and the contact tip; and (d) a gaspassageway formed at least partially by the nozzle for receiving the gasstream from the remote source and extending longitudinally forwardlyfrom the diffuser, the gas passageway having an outlet opening orientedto direct the stream flowing through the gas passageway to converge withthe longitudinal axis of the central bore of the diffuser at aconvergence point located forwardly of the nozzle assembly, the gaspassageway including a rear section in gas receiving communication withthe diffuser and a forward section angled inwardly in the forwarddirection.
 13. The conversion convergent nozzle assembly according toclaim 12, wherein a connection cavity is formed at least partially bythe diffuser for receiving the gas stream from the remote source, therear section of the gas passageway being in gas receiving communicationwith the collection cavity.
 14. A convergent nozzle assembly to convertan inert gas shielded welding unit into an arc cutting and gouging torchcomprising:(a) a cylindrical diffuser having a central longitudinal boresized to permit passage of a continuous wire electrode and a stream ofgas sufficient to blow molten metal away from the location at whichcutting or gouging is occurring, the diffuser also having at least onehole extending laterally through the diffuser in communication with thecentral bore of the diffuser; (b) an electrically conductive contact tipextending forwardly from the diffuser, the contact tip having a centralbore sized to slidably and closely receive the wire electrode; (c) anattachment collar snugly engaged over the diffuser at a locationrearwardly of the lateral diffuser holes; (d) a longitudinal nozzleextending over the diffuser and the contact tip, the nozzle including acylindrical section having a rearward internal counterbore snuglyengaged over the attachment collar and extending forwardly of the collarand the lateral diffuser holes to define a collection cavity within thecylindrical section in gas receiving communication with the lateraldiffuser holes, the cylindrical section also having a forward bore incommunication with the rear counterbore of the cylindrical section andsized to snugly engage over the diffuser at a location forwardly of thecollection cavity; and (e) a gas passageway extending through thecylindrical section forwardly from the collection cavity, the gaspassageway having an outlet opening oriented to direct the gas streamflowing through the gas passageway to converge with the longitudinalaxis of the central bore of the diffuser at a convergence point locatedforwardly of the nozzle assembly.